text: Ring strain theory was first developed by German chemist Adolf von Bayer in 1890.  Previously, the only bonds believed to exist were torsional and steric; however, Bayer's theory became based on the interactions between the two strains.  
  Bayer's theory was based on the assumption that ringed compounds were flat. Later, around the same time, Hermann Sachse formed his postulation that compound rings were not flat and potentially existed in a "chair" formation.  Ernst Mohr later combined the two theories to explain the stability of six-membered rings and their frequency in nature, as well as the energy levels of other ring structures.